A vehicle typically includes a heating, ventilation, and air-conditioning (HVAC) system which maintains a temperature within a passenger compartment of the vehicle at a comfortable level by providing heating, cooling, and ventilation. Comfort is maintained in the passenger compartment by an integrated mechanism referred to in the art as an air-handling unit. The air-handling unit conditions air flowing therethrough and distributes the conditioned air throughout the passenger compartment.
The air-handling unit commonly employs a housing having a network of conduits formed therein. The housing further includes a plurality of control dampers associated with the network of passageways for selectively controlling the flow of the air to various vents within the passenger compartment of the vehicle, depending on an operating mode selected by an occupant of the vehicle. For example, the flow of the air may be selectively provided to a first vent of the passenger compartment by rotatably opening and closing a first one of the control dampers.
In an arrangement for sealing one of the passageways in a housing according to the prior art, the control dampers have sealing elements made of a resilient material, and the housing has what is known as a seal face extending around an entirety of the passageway.
The use of resilient materials, such as polymers, to produce sealing elements is advantageous, as the resilient materials deform elastically under tensile and compressive stress, and afterward, return to the non-deformed state. For example, when the control damper is actuated to close one of the passageways, the sealing element is placed against the circumferential seal face. Any passage of air through the passageway is thereby prevented. Conversely, when the control damper is actuated to open the passageway, the passageway is opened by a release or pulling away of the sealing element from the seal face, thereby enabling the passage of air through the opening.
The sealing elements may be arranged on one or more sides or edges of the control damper. If the control damper is embodied as a door, for example, the sealing elements are provided on three sides of the control damper, while the hinge side of the door-type control damper has a separate sealing means, in most cases.
Sealing elements that are flat in shape, referred to as sealing lips, are known in the prior art. These sealing elements rest with a portion of a surface thereof against the seal face of the housing.
When the flat sealing lips are used to close a passageway, noises can be produced since there is a moment during the closing process when the pressure exerted by the fluid against the sealing lip is greater than the elastic force urging the sealing lip against the seal face. The pressure exerted by the fluid causes the sealing lip to move away from the seal face. The pressure of the fluid then decreases, allowing the seal to return to the position on the seal face. The process repeats continuously, until the spring force of the sealing element is greater than a force generated by the pressure of the fluid.
The repeated process of the rubber sealing lip being on the seal face and caused to move away from the seal face results in a fluttering of the rubber sealing lip, with the concomitant noise generation. The problem of audible noises or perceptible vibrations in motor vehicles or machinery is known as NVH (noise, vibration, harshness). The noises are perceived by passengers in a motor vehicle, for example, as bothersome and unpleasant. Therefore, it is desirable to eliminate the noises to improve passenger comfort.
To reduce the noise generation, various sealing elements that have recesses or cutouts in the edge region of the rubber sealing lip have been utilized. The recesses ameliorate the generation of noise during a closing process by preventing the simultaneous placement of the rubber sealing lip along the seal face. The closing process is completed only when greater contact pressure is achieved by the control damper.
It is a disadvantage of the recesses that, although the recesses in the rubber sealing lip prevent noises, no distinct closing mechanism is provided. The doors are sealed by overpressure, however there is no distinct sealing edge that ensures sealing. Thus, with the recesses, leaks can occur when the arrangement is moved to the closed position.
As shown in FIG. 1, also known from the prior art are embodiments having thickened areas formed at the end of a flat sealing element 100. The thickened areas are designed to reduce noise generation during the closing process, and to improve the seal tightness of the arrangement. Accordingly, the thickened areas may be designed as extending along the seal face of the housing 102 to close off the opening.
A sealing element 100 having the thickened areas may be made from an elastic material and referred to in the art as “frog finger sealing”, wherein improved sealing performance is achieved. In particular, a distinct closing edge is formed, and as a result, the tightness of the seal of the structure is improved when the passageway is in the closed position.
The closure of the passageway is achieved by the placement of the thickened end portion of the sealing element 100 against the seal face of the passageway by rotating the control damper in a direction indicated by the arrow in FIG. 1. However, a hissing noise can be generated, particularly when the sealing element leaves a narrow gap 104 between the sealing element 100 and the seal face of the housing 102 just before the final sealing.
Accordingly, there exists a need in the art for a control damper for a passageway capable of minimizing noise during a closing process while simultaneously providing a maximized seal tightness when the control damper is in the closed position.